By all odds, Hanna Greally ought to have lived a free life. From training as a nurse in 1940s London, she returned to Ireland and cared for her sick mother. But one day she arrived in a psychiatric hospital. Hanna was told she needed a rest. The staff were told she had suffered a nervous breakdown.

The wrongful incarceration – spanning 18 years – was documented in Hanna Greally’s 1971 memoir Birds’ Nest Soup. It’s now the basis of Gill McCaw’s nimble new monologue for Floating World Productions, in association with the Civic Theatre and First Fortnight mental health festival. It’s a raw reminder that Ireland locked up more mentally ill people in the 1950s than anyone else.

Here, we find Hanna dutifully played by Andrea Scott, glancing at us as she slowly disrobes from ordinary dress into a hospital gown. It’s as if Scott and McCaw’s production, informed by Ireland’s appalling institutional history, suspects an audience, no less than a society, as accountable. Other suspicions are equally discreet – visits by Hanna’s indifferent mother, for instance, are punctuated by the ring of a church bell.

McCaw’s script roves lightly through the psychiatric hospital – fondly called the Big House – and shows the labour-intensive laundry room and the carpentry (where they build coffins). It touches on meagre meals and, starkly, thoughts of suicide. The patients are from different walks of life. One woman wilfully admitted herself as an act of independence, another is returned every few months – whenever her husband tires of her.

The biggest indignation here is the imprisonment of citizens for the sake of convenience. Hanna learns she’s in the Big House because there’s no room for her at home. Her mother has taken over her bedroom. The injustice should set the production on fire.

Surprisingly, this remains a polite delivery of an outrageous story. The devastating amount of time passed in the Big House comes as something of an understatement. ‘Fourteen years gone,’ Hanna pouts, ‘and little rest in that.’ Sure, the production moves through scenes of isolation and despair but without delirium and, ultimately, any friction.

Floating World Productions have found affecting stage imagery before, and its telling that the lasting moments come from the fusion of Scott’s poised movement and Trevor Furlong’s imaginative audio-visual design. Together, they show the distressing effects of medical treatments like electric shock therapy. Those abstractions are new ways of seeing old history.

The production bows out with ghostly photographs of the Big House and of Hanna herself, glowing after being through it all. McCaw’s play is more interested in celebrating survival than anything. Hanna, there she was.

Lunatic, There I Go is on until 6 January 2018 at the Civic Theatre in Dublin. Click here for more details.